Required according to RFC 3986:

> An implementation should accept uppercase letters as equivalent to
> lowercase in scheme names

Closes #330

Since 7d353bbe, _GNU_SOURCE is always
defined, which implies __USE_MINGW_ANSI_STDIO and thus switches to
the mingw implementations of the printf() family.  That's
standards-compliant, unlike Microsoft's CRT implementations.

No longer a problem with NDK r16.

Only _WIN32 is defined by the compiler, and WIN32 is not standardized
and may be missing.

Closes #169

.. and not the stack buffer.  This made the AllocatedString destructor
crash.

Closes #52

The "pure" and "const" attributes are not so well-defined, and a
recent clang version implements an optimization which pushes the
definition's boundary beyond what I believed it was.  clang now
assumes that functions declared "pure" cannot throw exceptions, even
if they lack the "noexcept" specification.

When compiled with this new clang version, MPD will crash randomly if
an exception happens to get thrown by such as "pure" function
(https://github.com/MusicPlayerDaemon/MPD/issues/41).

This commit removes all such misplaced "pure" and "const" attributes,
closing #41.

This eliminates some overhead, because the compiler doesn't need to
consider these functions throwing.

Just in case.

GCC7 outputs the following error without this change:

    src/util/ReusableArray.hxx:61:35: error: no matching function for call to ‘swap(size_t&, const size_t&)’
       std::swap(capacity, src.capacity);

which can be resolved by just using an rvalue-reference rather than a
const rvalue-reference.
Signed-off-by: Ben Boeckel <mathstuf@gmail.com>

Move code from SongFilter.cxx.

The C++ compiler will auto-generate move and copy
constructors/operators for us.

Similar to boost::scope_exit, but fewer include dependencies.

Replaces the old BoundMethod template.